State of GPIB handshake lines
HandshakeStatus is a structure array that contains the fields DataValid, NotDataAccepted, and NotReadyForData. These fields indicate the state of the Data Valid (DAV), Not Data Accepted (NDAC) and Not Ready For Data (NRFD) GPIB lines, respectively.
HandshakeStatus can be on or off for any of these fields. A value of on indicates the associated line is asserted. A value of off indicates the associated line is unasserted.